Studies on illumination devices in which light emitting elements such as light emitting diodes (LED), electroluminescence (EL) elements, etc. are used have been developed since before. Among these, an illumination device using, as a light source, a LED module obtained by mounting a plurality of LEDs on a substrate has the advantage of a long lifetime as compared with a conventional illumination device using an incandescent lamp or the like as a light source. Therefore, the foregoing device potentially may substitute for the existing illumination devices in the future.
However, since the light emitting element such as a LED emits an abundance of heat at the time of emitting light, in the case where such a light emitting element is used in an illumination device, it has been necessary to provide a heat sink (heat radiating member) on a back side of the substrate on which the light emitting element is mounted (see, for instance, JP-2004-253364-A).
FIG. 5 is a perspective view illustrating an illumination device proposed by JP-2004-253364-A. As shown in FIG. 5, an illumination device 100 has three LED modules 101, 102, and 103, a module socket 104 in which the LED modules are loaded, and a heat sink 105 attached to a back side of the module socket 104. Since the heat sink 105 is provided with fins 105a, the illumination device 100 is capable of efficiently radiating heat generated by the LED modules 101, 102, and 103.
However, the illumination device proposed by JP-2004-253364-A has a massive heat sink, and hence there is the risk that the degree of freedom in designing devices that make use of the LED modules may decrease.